* {
  /* 初始化 */
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  height: 100vh;
  /* 弹性布局 居中显示 */
  /* display: flex;
  justify-content: center;
  align-items: center; */
  /* 渐变背景 */
  background: linear-gradient(to top left, #aeff9f, #5c8831, #156102);
  /* 溢出隐藏 */
  overflow: hidden;
}

.container {
  text-align: center;
  color: #fff;
}

.container h1 {
  font-size: 40px;
  font-weight: 100;
  letter-spacing: 2px;
  margin-bottom: 15px;
  /* 过渡效果 */
  transition: 1s ease-in-out;
}

.form {
  display: flex;
  flex-direction: column;
  align-items: center;
  position: relative;
  z-index: 2;
  opacity: 1;
  /* 不透明度改变时的过渡效果 */
  transition: opacity 0.5s;
}

.form input {
  outline: none;
  border: 1px solid rgba(255, 255, 255, 0.4);
  background-color: rgba(255, 255, 255, 0.2);
  width: 250px;
  padding: 10px 15px;
  border-radius: 3px;
  margin: 0 auto 10px auto;
  text-align: center;
  color: #fff;
  font-size: 15px;
  transition: 0.25s;
}

.form input::placeholder {
  color: #fff;
  font-size: 14px;
  font-weight: 300;
}

.form input:hover {
  background-color: rgba(255, 255, 255, 0.4);
}

.form input:focus {
  background-color: #fff;
  width: 300px;
  color: #174e01;
}

.btn-login {
  outline: none;
  background-color: #fff;
  color: #174e01;
  border: none;
  width: 250px;
  padding: 10px 15px;
  border-radius: 3px;
  font-size: 15px;
  cursor: pointer;
  transition: 0.25s;
}

.btn-login:hover {
  background-color: #f5f7f9;
}

/* 背景方块 */
.bg-squares {
  list-style: none;
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: 1;
}

.bg-squares li {
  width: 40px;
  height: 40px;
  background-color: rgba(255, 255, 255, 0.15);
  position: absolute;
  bottom: -160px;
  /* 执行动画：动画名 时长 线性 无限次播放 */
  animation: square 20s linear infinite;
}

/* 为每一个方块设置不同的位置、大小、动画延迟时间、动画时长、背景色 */
.bg-squares li:nth-child(1) {
  left: 10%;
}

.bg-squares li:nth-child(2) {
  left: 20%;
  width: 80px;
  height: 80px;
  /* 动画延迟时间 */
  animation-delay: 0.s;
  /* 动画时长 */
  animation-duration: 10s;
}

.bg-squares li:nth-child(3) {
  left: 25%;
  animation-delay: 4s;
}

.bg-squares li:nth-child(4) {
  left: 40%;
  width: 60px;
  height: 60px;
  background-color: rgba(255, 255, 255, 0.25);
  animation-duration: 22s;
}

.bg-squares li:nth-child(5) {
  left: 70%;
}

.bg-squares li:nth-child(6) {
  left: 80%;
  width: 120px;
  height: 120px;
  background-color: rgba(255, 255, 255, 0.2);
  animation-delay: 3s;
}

.bg-squares li:nth-child(7) {
  left: 32%;
  width: 160px;
  height: 160px;
  animation-delay: 7s;
}

.bg-squares li:nth-child(8) {
  left: 55%;
  width: 20px;
  height: 20px;
  animation-delay: 15s;
  animation-duration: 40s;
}

.bg-squares li:nth-child(9) {
  left: 25%;
  width: 10px;
  height: 10px;
  background-color: rgba(255, 255, 255, 0.3);
  animation-delay: 2s;
  animation-duration: 40s;
}

.bg-squares li:nth-child(10) {
  left: 90%;
  width: 160px;
  height: 160px;
  animation-delay: 11s;
}

.container.success h1 {
  transform: translateY(75px);
}

.container.success .form {
  opacity: 0;
  visibility: hidden;
}

/* 定义动画 */
@keyframes square {
  0% {
    transform: translateY(0);
  }

  100% {
    transform: translateY(-120vh) rotate(600deg);
  }
}